Replace the faulty Glow Plugs and restore proper operation in your 2011-2016 Ford 6.7L Powerstroke. When a glow plug fails to work properly, the combustion chamber doesn't have the necessary heat that can be required to help ignite the fuel. Depending on the outside temperature, it may take several attempts at starting the vehicle before achieving ignition. In freezing winter temperatures, it is possible for a diesel engine to not start at all without operational glow plugs. Commons symptoms of a bad glow plug can include a check engine light, hard starting, misfire/rough idling, loss of power, white or black smoke, or a decrease in fuel economy. A glow plug is a heating element that heats incoming fuel and air to encourage efficient fuel combustion in a diesel engine. This heat can be necessary for a diesel engine to start, run, and function optimally especially in colder weather conditions. Each cylinder of your engine typically has one glow plug, either in the pre-chamber or in the combustion chamber. Replace your glow plugs, harnesses, or control module/controller and shop all the top manufacturers such as Diesel RX, Dorman, Bostech, Ford/Motorcraft, Dtech, Alliant Power, GM/AC Delco, and Diamond Advantage By Navistar.